Ni(II)-Pyrazolate Framework Bearing a Metalated Schiff-Base Moiety for Electrocatalytic Hydrogen Evolution

Abstract

A robust and porous Ni-based metal–organic framework (MOF), NiL1, was assembled from Ni(II) ions and a dipyrazolate linker (L1 2–). A Ni(II)-anchored MOF catalyst Ni@NiL1-Sal has been successfully prepared by post-synthetic modification (PSM) condensation between NiL1 with salicylaldehyde, followed by chelation of Ni(II) ions by salicylaldimine as a secondary active site. Ni@NiL1-Sal with carbon black was found to exhibit enhanced electrocatalytic hydrogen evolution reaction (HER) performance (the smallest overpotential, 384 mV, and Tafel slope, 87 mV dec–1) when compared with primitive NiL1 and NiL1-Sal. Such improvement in HER highlights the creation of unambiguous secondary active sites as an avenue to the rational design of a functional MOF-based electrocatalyst.

Removing Perfluoro Pollutants PFOA and PFOS by Two-Pronged Design of a Ni8-Pyrazolate Porous Framework

“…The alkaline function merits extra attention as MOFs (especially carboxylate ones) are especially sensitive to and incompatible with alkaline conditions (due to facile hydrolysis of the metal node). For this, we choose the 3D Ni 8 -pyrazolate network as the scaffold as softer Ni–N links therein provides for more alkaline stability (e.g., even at pH = 14). − This framework system is also less prone to partial collapse upon activation as is the case for many Zr–carboxylate systems. − Recently, linker deficiency has been discovered in this MOF system, − offering open metal sites for anchoring additional alkaline ligands for functionalization.…”